1. Field of the Invention
This invention relates to an exhaust manifold/header as used in engines in motorized vehicles, for example, aircraft, automobiles, and stationary power plants.
2. Description of Related Art
Conventional internal combustion engines use a manifold or header apparatus with a single tract, each tract attached to each exhaust ports to collect exhaust gases from the individual ports. These exhaust gases result from the conventional combustion processes which occur in internal combustion engines. The exhaust manifold/header assists in improving engine output or efficiency by the following process. As the exhaust gases leave a combustion chamber within the engine cylinder head, these exiting gases create a slight vacuum or scavenging.
The scavenging assists in removing the remaining exhaust gases and helps to bring in additional intake charge. This exhaust process assists the intake charging process because an intake valve begins to open while an exhaust valve is still open. When the intake and exhaust valves are opened simultaneously, this event is termed overlap. Because of overlap, the exhaust process assists in the intake charging process. Design of valve overlap uses the exhaust system design features as a design parameter. The dimensional features of the exhaust tract greatly influence the degree to which intake charging is assisted by the exhaust gases. Thus current manifold or header design technology can use only the dimensional properties of the single tract.
The next effect the exhaust tract is required to complete is to create a negative pressure behind the closed exhaust valve. The purpose of the negative pressure at the exhaust valve is to assist the next cycle of extracting the combustion products. As the exhaust valve opens, the vacuum created by the previous exhaust gas flow process aids the exhaust gas flow into the exhaust tract. Therefore, the dimensional features of the exhaust tract greatly influence the degree of exhaust gas extraction.
Various multiple exhaust systems have been conventionally used. For example, U.S. Pat. No. 5,072,583 (Urushihara et al.) discloses the use of an exhaust system for internal combustion engines utilizing multiple exhaust passages. These exhaust passages are used to allow for higher engine torque. Also in U.S. Pat. No. 5,729,973 (Zander et al.), an exhaust collector with multiple tubes for reducing heat losses in the exhaust system is disclosed. However, both these examples, as well as many others currently in the art, utilize the use of exhaust ports in fluid communication through singular exhaust tracts converging into a singular common exhaust tract.
The conventional single exhaust tract has only a single set of operating capabilities, which are limited by the physical dimensions of the single tract. The single operating capabilities include single exhaust gas speed, exhaust flow rate, backpressure, cylinder scavenging rate, exhaust temperature profile and sonic velocity. Therefore, there is a need for exhaust tracts having multiple operating capabilities which would increase engine performance.